Star trails at Arrow Glacier, 16,000 feet up Mt. Kilimanjaro, Tanzania, Africa. Southern Star on horizon, cloud cover at 10,000 feet lit underneath by the town of Arusha. From my series on <a href="http://www.danheller.com/tanzania.html">Tanzania</a>.

Technical details: Canon EOS 1v Body, EF 17-35mm f2.8 lens (@17mm),Tiffen FL-D filter, Velvia film (rated at 40ASA),3.5 hour time-release exposure.

This shot is interesting for a variety of reasons. First, the lightingof the tents was very lucky. I hadn't intended to get them lit at all,but as people got up during the night to go to the latrine, theirflashlights lit the interiors of the tents as they moved around.(Altitude causes frequent visits to the latrine, especially at night.)

Second, because the night had no moon, I was concerned there wouldn'tbe enough light on the ground to give the scene some context. But, as itturns out, the ground was lit entirely by starlight. That seemsamazing, especially because stars are normally not bright enough to dothat. However, at 16,000 feet, the air is so thin and there is no otherlight pollution around that the Milky Way is like a huge light bandacross the sky. You can sort of make it out by a cone-shaped glow inthe middle of the image from the top down to the horizon.

Another other lucky factor was that the night temperature drops belowfeezing at that altitude. Frost or other elements could have ruined thepicture simply by building up on the lens, the camera's battery dying,or by the camera simply not functioning at all. Yet, nothing went wrong.

Fun things to note:
The green hues on the horizon is the cloud cover at 10,000 feet beinglit by the lights from the towns below. They use mostly flourescentlights to save energy, and as you know, those tend to glow green on film.

Normally, long exposures with Velvia film causes a color shift on thefilm's emulsion, so that the green layer exposes more than the blue orred layers. I added the FL-D filter to compensate for this. This is apurplish filter that normally turns the green hue of flourescent lightsto white, but it doesn't really do that very well. However, it does agreat job of correcting the green color shift in very long night exposures.(The green from the flourescent lights was compounded by the green shiftfrom the long exposure, so the FL-D just put the light back to normal,which means that green flourescent lights just remained green.)

The reddish color just above the horizon, fading to blue higher up, iscaused by the red dust kicked up from the ground below. Tanzania didn'thave a lot of rain this season, and the last wet season was also particularlydry. As a result, the dryness caused a lot of the red dirt to fly everywhere.

Lastly, note the southern star just above the horizon. That's not visible inthe northern hemisphere. It points south, but not quite the same way Polaris points due north. (There is a small arc.) However, it's close to the horizon because Kilimanjaro is only 3-degrees south of the equator. If we were further south, it'd be higher in the sky.